Use HDMI out for audio only?

[Colonel Sanders]

Hey everyone,

I have a 780 Ti hooked up to a BenQ XL2720Z which has DP and HDMI connections. The DP is going direct to my PC, and the HDMI goes from my PC to my Pioneer AVR then to the HDMI input on the monitor.

The idea is I game on my PC at 144hz goodness, and use my 5.1 setup pumped through the AVR, which sounds amazing. I can also select the BenQ's HDMI port when I want to use my PS4 or Xbox.

That all works fine, the problem is that in order to put sound through the AVR, Windows wants me to have it also selected as a display. If I deselect as a display in the Nvidia Control Panel, then I also lose it as an audio output option.

Does anyone know if there is a way to "turn off" a display in Nvidia Control panel while keeping the HDMI audio?

edit: At the very least, is it possible to simply "seperate" a second display so that the mouse or keyboard can't access it without a specific shortcut or something? Cloning doesn't work because Windows then forces the drawing of animations and scrolling to 60hz to match the HDMI output.

 

[t1337Dude]

It's not possible. HDMI must send video signal in addition to audio signal. You need to get DDMM (dual display mouse manager) to prevent issues of mouse disappearing. If you use a calibrated color profile, you might need Color Profile Keeper too (color calibrations will cause conflicts and revert on their own). Would be great if they allowed us to accept the audio signal and ignore the video signal - but it's not an option.

Also, I generally recommend not hooking the PC display up to the receiver directly - it'll contribute to your input-delay chain (HDMI processing and what'not) , but how much varies on the receiver.

 

[Colonel Sanders]

Thanks! I'm thinking what I might just do is forgo HDMI altogether from the PC and just run optical audio out from the motherboard onboard audio to the AVR. Are there any downsides to onboard audio through optical vs. what the Nvidia card pumps out?

And yeah, I hook the PC up direct to the display, it's only the audio that is going through the AVR. Well, except for the "second display" (which is just the HDMI input on the same monitor.)

 

[t1337Dude]

Optical is limited to 2CH PCM, DDL, and DTS - also it doesn't go higher than 48khz. So unless you're requiring multichannel PCM or the ability to play super-high quality music rips, then there's nothing you'll be missing out on.

 

[Colonel Sanders]

Thanks for the info.

 

[Sycraft]

As others have said, you need a video signal of some kind since audio data is transmitted during the vblank period. It can be blank (blackburst) but there's no way to make video cards do it. There's not really any good option for "HDMI as audio only" for computers. I wish you could tell video cards to do that, but you can't.

It is actually something I've spend a lot of time on and there's no good long term solution, so eventually I'm going to just ditch my AVR and replace it with an RME card and redo things with pro speakers.

Right now there are two solutions I know of to be able to do HDMI audio without having to have a video out on your computer:

1) An Auzentech HTHD card. You have to give it a video source to get sync, but you can use a DVD/blu-ray player, signal generator, or whatever else you like. Works well actually and is what I do... but they stopped selling those cards some time ago, and also stopped with drivers. So not a long term solution.

2) Get a MOTU HD Express/HDX-SDI. They are video capture/output devices. However they know how to do a blackburst signal and do audio over HDMI when there's no video signal. Works great for professional ASIO applications, but it doesn't have surround support for Windows programs, just stereo, because of the way it enumerates its output. Also expensive.

As a practical matter there is little, if any, perceptible quality difference between DTS Connect over optical and LPCM over HDMI, even on very high end systems. So unless you are insane like me and want to go to great lengths to try and make it all work, just use DTS and call it good.

If your motherboard supports it, you can use that for most things. If not Creative makes a cheap unit that'll do the trick. This one can also route speakers to the S/PDIF out which is necessary for some stupid games (looking at your Assassin's Creed) to do surround sound because they don't recognize the digital output as surround. They also make a more expensive internal unit that'll do the trick and has ASIO support and such if you wish that.

 

[DoubleTap]

It's even more of a pain when you run NV Surround.

I bought an accessory monitor not so much because I needed it, but because I wanted surround sound.

My motherboard does not have DDL or DTSC encoding and I don't have any slots to add a sound card so my only options were to use a USB sound card and I found that most of them added significant latency - especially the ASUS UX7.

My advice would be to add a second monitor or possibly just run two screens and run the second monitor to your HDMI input on your single monitor. You will probably need a Gefen HDMI detective so your system does not detect when it's connected/disconnected and you will need to deal with keeping everything on one screen, but it's doable.

They sure don't make it easy though.

NV Surround adds several layers of difficulty, but some of what I did might be useful to you:
http://hardforum.com/showthread.php?t=1802259

 

[Colonel Sanders]

Thank you both for all the good info!

As a practical matter there is little, if any, perceptible quality difference between DTS Connect over optical and LPCM over HDMI, even on very high end systems. So unless you are insane like me and want to go to great lengths to try and make it all work, just use DTS and call it good.

I have an Asus Sabertooth Z77 which has a Realtek ALC892 built in. I can't tell if it supports DTS Connect. All I can see is that when I go to the Properties panel on the Realtek Digital Output (Optical) I can see "supported formats" of DTS Audio, Dolby Digital, and Microsoft WMA Pro Audio. Would the DTS Audio indicate DTS Connect capabilities? If so, do most games output with proper surround sound that way? One thing I love about the HDMI output is that it's almost flawless with every game. Even older games that I never would have thought have surround sound work perfectly. I've read people have troubles with surround over optical but I don't know if that's because their particular sound devices didn't support DTS Connect or something.

Thanks again!

Edit: I put in an order for a Sound Blaster Z from Amazon. Screw the crappy onboard stuff.

 

[EdZ]

One option that may work would be to use display mirroring.
Ensure the DP connection is the primary display (otherwise you will get display tearing even with VSYNC on, due to all displays refreshing based on the primary display's refresh without genlocking, and will be limited to the primary display's max refresh rate), and that the mirrored HDMI display is set to use GPU scaling. This should allow for audio output via HDMI without the chance of your mouse ending up on the 'second' screen.

This only works if you have only the one monitor (i.e. no surround or multi-monitor), and if your AV receiver exposes itself as a display without a display connected to it (if not, connecting it's HDMI output to the monitor may work).

 

[Sycraft]

Edit: I put in an order for a Sound Blaster Z from Amazon. Screw the crappy onboard stuff.

Not that you need the info since you ordered this, but since you asked:

What you do is have a look at the format in advanced playback options. If you have Dolby Digital or DTS support, you'll be able to set it there. It will then handle all the encoding and such. However you'll notice two small issues:

1) Playback takes a second to start. When there's no sound being sent to the card, it stops the encoding stream, and when it restarts, there's some time for the AVR to get the decoding going. So you get a tiny bit cut off of the start of things.

2) Some programs are dumb and don't recognize it as a surround output. They look at it and say "Oh S/PDIF is stereo, I set stereo mode!" and won't change.

So what you can do with your fancy SB card is find an option, I can't remember where it is on the new ones, that redirects the speaker outs to S/PDIF and does encoding. Then you play sounds to the speakers, which you set to surround of course, and that gets taken and encoded and sent out of the S/PDIF ports. This makes stupid programs happy.

 

[t1337Dude]

One option that may work would be to use display mirroring.
Ensure the DP connection is the primary display (otherwise you will get display tearing even with VSYNC on, due to all displays refreshing based on the primary display's refresh without genlocking, and will be limited to the primary display's max refresh rate), and that the mirrored HDMI display is set to use GPU scaling. This should allow for audio output via HDMI without the chance of your mouse ending up on the 'second' screen.

This only works if you have only the one monitor (i.e. no surround or multi-monitor), and if your AV receiver exposes itself as a display without a display connected to it (if not, connecting it's HDMI output to the monitor may work).

I've tried this and it doesn't work for me. Maybe if you have a 1080P monitor, it might work, but when I do then, it limits my 1200P monitor to 1080P, making it an unworkable solution.

Honestly, with that DDMM (Dual display mouse manager) app, it really doesn't become that much of a problem anymore to just continue sending audio over HDMI.

 

[aldamon]

Most annoyingly, as I found out, is if you use a HTPC for music occasionally and have HDMI hooked up the receiver for audio and then turn off the TV to conserve power, the audio stream will die as well. Optical or coaxial digial fixes everything.

 

[DoubleTap]

Most annoyingly, as I found out, is if you use a HTPC for music occasionally and have HDMI hooked up the receiver for audio and then turn off the TV to conserve power, the audio stream will die as well. Optical or coaxial digial fixes everything.

This is why people use the Gefen HDMI Detective - if your PC is connected to a receiver, any time you switch inputs, it tells your PC that that screen is disconnected and your system has to reconfigure/reallocate everything and on some systems, it's glitchy trying to get the sound back.

The HDMI Detective sits between your PC and the receiver and it maintains the connection to your PC at all times - obviously if you switch your receiver to a Blu-Ray player, the PC audio won't play out, but your PC won't know that and everything will work perfect (and instantly) when you switch back to the PC.

They run $60-80 but I consider it invaluable and I wouldn't want to run my system without it.

http://www.amazon.com/Gefen-EXT-HDMI-EDIDP-HDmi-Detective-Plus/dp/B001RIMZUW/

 

[PepeLePew]

This is why people use the Gefen HDMI Detective - if your PC is connected to a receiver, any time you switch inputs, it tells your PC that that screen is disconnected and your system has to reconfigure/reallocate everything and on some systems, it's glitchy trying to get the sound back.

The HDMI Detective sits between your PC and the receiver and it maintains the connection to your PC at all times - obviously if you switch your receiver to a Blu-Ray player, the PC audio won't play out, but your PC won't know that and everything will work perfect (and instantly) when you switch back to the PC.

They run $60-80 but I consider it invaluable and I wouldn't want to run my system without it.

http://www.amazon.com/Gefen-EXT-HDMI-EDIDP-HDmi-Detective-Plus/dp/B001RIMZUW/

Sorry for the necro. Was there ever a better solution found?

 

[DoubleTap]

Sorry for the necro. Was there ever a better solution found?

I don't think so.

1. HDMI (EDIT emu needed)
2. Optical (multi channel encoders add latency when you use them for gaming)
3. Discrete Analog inputs (rare in mid-range gear and usually loses access to the DSP functions in the AVR)

 

[noko]

Sorry for the necro. Was there ever a better solution found?

I don't see why this would not work:
https://www.bestbuy.com/site/insignia-hdmi-audio-extractor-black/6324750.p?skuId=6324750

Use a dummy HDMI monitor plug with it and extract the audio from the stream. Setup up the desktop for multi-monitor, duplicate. When I use HDMI dummy plugs, Nvidia and AMD drivers load the audio drivers to it and I can switch audio to the HDMI dummy plug, of course nothing comes out of it.

 

[ashmelev75]

Use a dummy HDMI monitor plug with it and extract the audio from the stream. Setup up the desktop for multi-monitor, duplicate. When I use HDMI dummy plugs, Nvidia and AMD drivers load the audio drivers to it and I can switch audio to the HDMI dummy plug, of course nothing comes out of it.

You do not need a dummy HDMI plug and you do not need an HDMI audio extractor.

I have 2 DP monitors and an HDMI receiver without any monitor connected to it.
I have the sound directed to the receiver. I have the receiver and 2nd monitor duplicated in the display control panel, so the mouse cursor does not go to the monitor that does not exist.
The only issue is that the duplicated monitor is limited to 60Hz refresh because of the duplication.

 

[Nenu]

Optical is limited to 2CH PCM, DDL, and DTS - also it doesn't go higher than 48khz. So unless you're requiring multichannel PCM or the ability to play super-high quality music rips, then there's nothing you'll be missing out on.

Just posting to correct this 6yr old post.

Optical (SPDIF) is limited to 48KHz when using compressed multichannel DDL or DTS.
For stereo PCM it will go up to 24bit 192KHz if your optical cable is good enough.